NGC 1566
A nearby Seyfert galaxy with strong spiral arms and an active nucleus.
NGC 1566, nicknamed the Spanish Dancer, is an intermediate spiral galaxy about 69 million light-years away in the constellation Dorado. Its exact distance is uncertain, with measurements spanning a range. Scottish astronomer James Dunlop discovered it on May 28, 1826; at 10th magnitude, it requires a telescope to see.
It belongs to the NGC 1566 subgroup of the Dorado Group, where it is the dominant and brightest member, though some studies list NGC 1553 as brighter. The group’s X-ray emission comes mostly from NGC 1566’s hot gas halo, which extends outward until it merges with the background. The galaxy appears to interact with smaller subgroup members. Radio observations show an asymmetrical disk, and its neutral hydrogen gas is mildly warped.
Its morphological classification is SAB(rs)bc: a spiral with a weak bar (SAB), an incomplete ring around the bar (rs), and tightly wound arms (bc). The spiral arms are strong and symmetrical. The galaxy’s plane is tilted at an angle to Earth’s line of sight, with its long axis oriented at a specific position angle. The northwest side is more dust-obscured, indicating it is the near side. The ratio of neutral hydrogen mass to stellar mass is 0.29, high for a galaxy of this mass. Its absolute luminosity and H I content are known.
NGC 1566 is an active galaxy with many Seyfert type I features, though its exact type is uncertain. It is one of the closest and brightest Seyfert galaxies. The central supermassive black hole’s mass is estimated. Its proximity, strong spiral arms, and active nucleus make it a frequent subject of study. It is the nearest known CL AGN galaxy.
Three supernovae have been observed: SN 2010el (Type Iax, magnitude 16.8), discovered on June 19, 2010, located west and south of the galaxy’s center; ASASSN-14ha (Type II, magnitude 14.6), found on September 10, 2014, by the All Sky Automated Survey for SuperNovae; and SN 2021aefx (Type Ia, magnitude 17.24), discovered on November 11, 2021, by the Distance Less Than 40 Mpc Survey, which later reached magnitude 12, the brightest supernova of 2021.
Quick Facts
- Epoch
- J2000
- Ra
- 04 · 20 · 00.40200
- Dec
- −54 · 56 · 16.5781
- Z
- 0.005017
- Dist Ly
- 21.3 Mpc
- Appmag V
- 9.73 · 0.03
- Constellation Name
- Dorado
- Names
- PGC 14897
Facts from the source article.
Lore & Background
NGC 1566 was discovered on May 28, 1826 by Scottish astronomer James Dunlop. At 10th magnitude, it requires a telescope to view. The galaxy is the dominant and brightest member of the NGC 1566 subgroup of the Dorado Group, though some listings place it as second brightest after NGC 1553. The X-ray emission from the group is dominated by the hot gas halo of this galaxy, which extends out before merging with the background radiation. The galaxy appears to be interacting with smaller members of its subgroup, and radio emissions suggest the disk is asymmetrical with a mild warp in the neutral hydrogen gas.
The morphological classification of NGC 1566 is SAB(rs)bc, indicating a spiral galaxy with a weak bar structure around the nucleus, an incomplete ring around the bar, and wound arms. The spiral arms are strong and symmetrical. The northwest side of the galaxy is more strongly obscured by dust, suggesting it is the near side. The mass ratio of neutral hydrogen gas to the mass of the stars is 0.29, which is on the high side for a galaxy of this mass. NGC 1566 is an active galaxy with many features of a Seyfert type I, although the exact type remains uncertain. The mass of the supermassive black hole at the center is estimated at a certain value, and the galaxy is the nearest known CL AGN galaxy.
Reader's Guide
NGC 1566 holds significance as one of the closest and brightest Seyfert galaxies, making it a key subject for studying active galactic nuclei. Its proximity, combined with strong spiral arms and an active nucleus, has led to extensive scientific study. The galaxy's uncertain distance, with measurements ranging, and its debated status as brightest or second brightest in its group highlight ongoing research. Three supernovae have been observed in NGC 1566: SN 2010el (Type Iax, mag. 16.8) discovered on 19 June 2010, ASASSN-14ha (Type II, mag. 14.6) discovered on 10 September 2014, and SN 2021aefx (Type Ia, mag 17.24) discovered on 11 November 2021, which reached magnitude 12 and became the brightest supernova of 2021. The galaxy's high neutral hydrogen mass ratio and asymmetrical disk, along with its role as the nearest known CL AGN galaxy, contribute to its legacy as a valuable laboratory for understanding galaxy evolution and nuclear activity.
Did You Know?
- NGC 1566 is sometimes called the Spanish Dancer.
- It was discovered by Scottish astronomer James Dunlop on May 28, 1826.
More in Galaxy Clusters and Groups, Part 4 1-24
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